Tuyere for introducing oxygen and a protective medium into converter vessels

ABSTRACT

An improved system for supplying oxygen and a protective fluid to metal, below the surface of the metal, in refining vessels in which the tuyeres are connected separately to the supply of oxygen and the supply of protective fluid.

United States Patent [191 Knuppel et a1.

[11] 3,811,386 51 May 21, 1974 TUYERE FOR INTRODUCING OXYGEN AND APROTECTIVE MEDIUM INTO CONVERTER VESSELS [75] Inventors: Helmut Knuppel;Karl Brotzmann;

Hans Georg Fassbinder, all of Sulzbach Rosenberg, Germany [73] Assignee:Eisenwerke Gesellschaft Maxiniilianshutte m.b.II., Sulzbach Rosenberg,Germany [22] Filed: Dec. 8, 1972 [21] Appl. N0.: 313,377

[30] Foreign Application Priority Data Dec. 9, 1971 Germany 2160999 [52]US. Cl 110/1825, 122/66, 266/41, 277/110, 285/133 R [51] Int. Cl. F23il/00 [58] Field of Search 110/1825; 266/41;

[56] References Cited UNITED STATES PATENTS 3,703,279 1 H1972 Saccomanoet a1 266/41 2,410,912 11/1946 Wenk 3,076,642 2/1963 Dhenein.' 266/41Primary Examiner--Kenneth W. Sprague Assistant Examiner-James C. YeungAttorney, Agent, or Firm-Lawrence 1. Field [5 7] ABSTRACT An improvedsystem for supplying oxygen and a protective fluid to metal, belowthesurface of the metal, in refining vessels in which the tuyeres areconnected separately to the supply of oxygen and the supply ofprotective fluid. 1

7 Claims, 3 Drawing Figures FATENTEUMAY 21 1374 SHEEI 1 [IF 2FATENTEBHAY 2 1 i914 SHEET 2 (IF 2 This invention relates to a tuyerefor reliable introduction of oxidizing gases, and particularly oxygen,and a fluid, i.e., a liquid or gaseous protective medium surrounding theoxidizing gases, into a refining vessel, in which one or several tuyeresare mounted below the bath surface, for the purpose of refining metals,preferably pig iron, contained in said vessels.

Most recently a process has been carried into practice, whereby pig ironis refined by blowing-in refining oxygen below the bath surface,together with a liquid or gaseous protective medium of a converter. Thisprocess is described in the German Auslegeschrift Pat. No. 1,583,968,British Specification Pat. No. 1,253,581 and in U.S. Pat. No. 3,706,549issued December 19, 1972. The tuyeres for the refining gas and for theprotective medium consist essentially of two concentric tubes. Therefining gas, preferably oxygen, is passed into the vessel through theinner tube, while the liquid vor gaseous protective medium is passedinto the vessel through the annular space between the two concentricallymounted tubes. The annular space separation is approximately 1 mm and ismaintained by spacers between the two tubes, for instance by inner ribson the outer tubes. Preferably liquid or gaseous hydrocarbons, moreparticularly light fuel-oil, propane or natural gas, are used asprotective media for the oxygen jet so as to reduce tuyere burn-off andwear of the refractorymasonry. The concentric arrangement of the tuyeretubes passing through the refractory masonry into the refining vesseland terminating below the bath surface is achieved in fairly simplemanner by 'using spacers between the inner and outer tubes. A number ofprocedures for making spacers are known. Thus the spacers may consist ofcoils brazed or welded on the-inner tube, or they may be outer ribs onthe inner tube or inner ribs on the outer tube, or evenly distributedpoint-like elevations on either tube.

Whereas this part of the tuyeres may be so fashioned with simple meansas to be functionally and operationally reliable, supplying both tuyereducts with different gases raises appreciable difficulties.Constructional solutions for supplying-two different gases to tuyeresconsisting of concentric tubes are known. For instance, the GermanOffenlegungsschrift Pat. No. 2,003,339 describes a device for feedingthe blowing tuyeres of a steel converter. The known construction howeversuffers from several appreciable drawbacks in practice.

. Supplying the two gases is effected by a consolidated supply systemsub-divided into two chambers. This solution may lead to the undesirablemixing of the two gases in case of leaks. In particular, introducing acombustible protective medium through the annular space and oxygenthrough the refining gas tube may lead to dangerous fires and toexplosions if there is a leak in the supply system. Also, sealing meansmade of organic and elastic materials such as rubber have been foundunsuitable for usual converter operations, because impurities may damagethe seals and because they are'insufficiently temperature resistant.

To provide a tuyere for operationally reliable introduction of arefining gas together with a protective medium into a converter, thepresent invention proceeds from the consideration that high technicalrequirements together with easy handling under rough steelmakingoperations must be met with .respect to feeding the two fluids to thetuyeres made of two concentric a. the inner tuyere tube should be easilyremovable and interchangeable for the purpose of monitoring itsremaining length;

b. lek the fluids must be excluded in case of a leak in the supplysystem of either fluid;

c. any seals utilized must be operational at least up to temperatures of300 C and may not consist of soft, organic materials.

The improved device of the present invention consists of a tuyere inwhich an oxygen-containing gas flows through the inner duct and thehydrocarbo-' naceous medium flows through the outer duct, and whereinthe two media for the inner and outer ducts are so supplied as to'bespatially isolated from one another and the seals are fundamentally onlyin contact with ambient, so that sealing of both media with respect toeach other is avoided. Sealing is achieved by metallic components suchas conical and wedge rings and the like which are not susceptible to thetemperature instability of rubber and other organic seals.

The particularities of the device according to the invention whichachieve reliable operation of the refining gas tuyeres with protectivemedia will be better understood from the description which follows takenwith the drawings in which: 7

FIG. 1 is a longitudinal section through a tuyere con sisting of twoconcentric tubes in which the refining gas and the protective medium aresupplied according to the invention;

HO. 2 is a cross-section through the dual concentric tube tuyere of FIG.I; and

FIG. 3 is a longitudinal section similar to FIG. 1 showing theconnections of both tuyere ducts to their supply lines.

The tuyere for the refining gas and for one protective medium consistsof two concentric tubes 1 and 2. The outer tube 1 may be made of anysuitable material such as ordinary steel, copper or high grade steel.The outer tube 1 is provided with inner l8 3 which serve as spacers forthe inner tube 2. Outer tube 1 is inserted into the inner converterspace through a bore hole'4 in the converter jacket 5 and further passesthrough refractory masonry 6. As an example, steel member 5 may be 34converter bottom plate and tube 1 may be pressed into the refractorybottom lining. A welded flange 7 serves as a stop for outer tube 1 andfor securing it to the steel plates. In addition, outer tube 1 may berigidly connected by such fasteners as bolts to the steel plate 5 of therefining vessel. The outer tuyere tube 1 terminates outside the steeljacket directly below a seal 9.

In lieu of the usual fastening and sealing means between flange 7 andsteel plate 5, a particularly simple and temperature resistant sealbetween outer tube l .and bore hole 4 in the'steel plate 5 has been.found to very effective. Good results have been achieved by using aceramic putty preferably .a substance from the v SiO -AI Q, system thathas been mixed with water-glass and/or phosphoric acid solutions or withcement addi-- tion and water. Putty layer 8 serves as fastening andsealing means and is located between outer tube 1, and steel plate 5 upto flange 7. Besides being simple to inand cleaning following eachconverter campaign, as regards the tuyere ducts. I

The inner tuyere tube 2, provided for passage of the refining gas intothe converter and below bath surface, is inserted into the outer tuyeretube 1 which is provided with inner ribs. One particularly preferredinner tuyere tube material is a high-grade stainless steel with 18percent Cr and percent Ni. However, other metals such as copper orsteels differently alloyed may be used. In one installation, thedimensions of the tuyere tubes was as follows: 1

OUTER TUBE 1, OD 28 mm, ID 24 mm, maximum rib height 1 mm; INNER TUBE 2,OD 22 mm, ID 18 mm.'As shown, inner tube 2 is longer than outer tube 1,because,'although both tuyere tubes terminate at the converter innerside, inner tube 2 extends beyond outer tube 1 at the converter outerside. A suitable difference in length is 150 mm in the installationshown. I

The annular space subtended between outer tube 1 and inner tube 2 mustbe sealed against the outsides of both gas supply tubes. A sleeve 10 isbrazed or welded to inner tube 2. A clamping nut ll together withmetallic sealing ring 9, which may be a wedge, double wedge or'conicalsealing ring or the like, seals outer tube 1 with respect to the ringspace 12. Feed tube 14 for the liquid or gaseous protective medium iswelded into the bolting connector 13. Corresponding to the clamping nut11 and sealing ring 9 of the outer tube, clamping nut 15 and sealingring 16 seal off inner tube 2 with respect to the ring space 12. Thelengths of the bolting connector 13 and of sleeve 10, which is brazed onthe inner tube, thereby determine the shifting latitude of the innertube in the longitudinal direction. In the present installation theshifting latitude amounts to about 25 mm.

A threaded joint between refining gas supply line 17 and inner tube 2 islocated below the protective medium supply line and the sealing elementsof the latter. Clamping nut 18 together with the metallic sealing ring19 serve as a seal of the refining gas feed line with respect to theinner tube. Because of the separation of the protective medium andrefining gas sealing elements, there can be no undesirable mixing ofthese media in case of leaks, since individually they aresealed onlywith respect to the ambient atmosphere and not with respect to eachother. The spacing between the two feed lines is only determined by theextension in length of the inner tube. Theoretically, the latter lengthmay be selected at will, but there are limits on mechanical grounds; inthe converter shown, the clear spacing 20 between the sealing elementsamounts to about 150 mm. Suitable fittings are provided between the gasor protective medium supply to the corresponding tuyere ducts and itsconnection to the associated supply lines, which serve to compensatedimensional inaccuracies when fitting the tuyere feed lines to thesupply lines. In order to connect the ring space 12 with the protectivemedium supply line 21, ordinarily straight and angular connectingpieces, and the displacement possibilities provided by these, willsuffice in view of the relatively thin conduit for feeding the liquid orgaseous protective medium. All the sealing means for this tuyere feedline for the protective medium are metallic wedge, cone and/or doublewedge rings and the like. Various regulatory means 22 are installed inthe tuyere feed line. These include, for instance, back-pressure valves,throttle restrictors for metering the protective medium and/orcontrollable switch-over and switch-off valves. Said regulating meansmay be installed and several may be arranged in parallel and/or inseries. Installation is efiected using mechanical sealing rings andstraight and angular connecting pieces. In the installation shown inFIG. 3, the line segment 14 between the supply line 21 and theprotective medium feed-in, is approximately 10 mm. Tube 14 is of copperor steel.

The tuyere feed line for the refining gas could be connected to thesupply line in the same manner as the protective medium line. Thus, fora tuyere of fairly small diameter, as may be the case for a refining gasfeed line, the outer diameter of which is less than 15 mm, theconnecting pipe between the refining gas feed-in and the supply line ispreferably U-shape and is connected using metallic sealing rings andfittings or connectors. As the tube diameter increases, that is, forlarger tuyeres, this arrangement no longer affords sufficient fittingclearance'when assembling, In such cases, that is, for diametersexceeding 20 mm, the construction shown in FIG. 3 was found to bepreferable. Anglepiece 23 is brazed or welded to tuyere inner tube 2,located to provide the desired safetyspacing 20 between the protectivemedium feed-in and angle-piece 23. This angle-piece 23 is provided witha maintenance-fitting 24 in an inner tube extension. Normally, themaintenance-fitting 24 will be blank-flanged and opened only formaintenance, for instance for measuring tuyere length or if necessary,for padding the inner tube with, say, a ceramic substance if thetuyere-were to break down.

The angle piece 23 is connected by means of a threaded fitting 25 and ametallic ring seal 26 to another angle-piece 27. Threaded fitting 25 isso designed that it allows a shift latitude'of about 25 mm in the tubeseal. A tube segment of any suitable length may be welded-in betweenthreaded fitting 25 and the angle piece 27. Angle-piece 27 is connectedvia 'a ball-andsocket joint 28 to the refining gas supply line 29.Balland-socket joint 28 permits rotation in any direction. Because ofthe feasibility of shifting provided in threaded fittings 15 and 25 andon account of ball-andsocket joint 28, any dimensional inaccuracies maybe easily accommodated when fitting the supply lines to the tuyeres. TheOD of the tuyere feed line in the example shown may be 25 mm for therefining gas. The feed line is made from ordinary steel tubing, thoughothermetal tubes may also be used, such as copper tubes or alloyed steeltubes.

The tuyere according to the invention and designed for the reliableintroduction of refining gas together with a protective medium besidessimple and reliable construction also is highly economical. It has beenfound in operation that elastic lines or springs or similar elasticconnecting means are not required. The elimation of sensitive, elasticconnecting pieces especially in the rough steel-making operations andelimination of the dangers of possible leaks in the feed linesrepresents an appreciable technical progress.

We claim: 7

1. In a combination with a tuyere passing through the steel mantle andthe refractory masonry of a convertor,

for reliably feeding oxidizing refining gases surrounded by a liquid orgaseous protective medium into a molten metal bath, said tuyere beingdisposed to discharge said fluids underneath the metal bath level, therefining gas being supplied to said molten metal through an inner tuyerepipe and the protective medium being supplied through an annular spacebetween the inner tuyere pipe and an outer, coaxial pipe, said outerpipe leading to a supply cap or head surrounding a sleeve of the innerthrough-pipe and a closure for the outer tuyere pipe; the improvementswhich comprise:

providing separate connections between said supply cap (13) and saidinner tuyere pipe (2) and spatially separate supply sources (21, 29)respectively, for the protective medium and the refining gas, meanshermetically sealing said sleeve peripherally with the inner tuyere pipe(2) by welding or soldering, metallic sealing rings located axially onboth sides of said supply cap for sealing said supply cap with respectto the outer typere pipe (1) and with respect to the sleeve (10), andmeans for axially tensioning said metallic sealing rings on both sides.2. A tuyere as defined in claim 1 including in addition clamping nuts orscrew caps (1, 15) mounted on the supply cap (l3) for tensioning thesealing rings (9,16), said sealing rings being detachable.

3. A tuyere as defined in claim 1 wherein the extremities of sleeve (10)and of the outer tuyere pipe (1) are axially separated from each otherand a longitudinally adjustable annular space (12) is formed betweenthem.

4. A tuyere as defined in claim 1 including, in addition a putty seal ormastic seal between the outer surface of the outer tuyere pipe (1) andsteel mantle (5).

5. In the tuyere as defined in claim 1, the metallic sealing rings (9,l6) and the putty or mastic (8) are each temperature resistant up to 300C.

6. A tuyere as defined in claim 4 wherein the putty or mastic consistsprincipally of SiO -Al O which is prepared from water glass and/orphosphoric acid solutions or with additions of cement and water.

7. A tuyere as defined in claim 1 including in addition ball jointconnections (28) mounted in the supply lines (17, 27, 14) to the outertuyere pipe (1) and to the supply cap (13).

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, ,3 6Dated May 21, 197

Inv )Helmut KnuDDel: Karl Brotzmann; Hans Georg Fassbinder It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Correct assignee to--Eisenwerk-Gesellsshaft Maximilianshutte Column 2,line 10; change "lek' to--mixin;;--

Column 2, line '5; change "18" to -ribs Column 2, line 49; change "3 4"to--the- Column 6, line 12-; delete "ll" Signed and sealed this 5th dayof November 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner ofPatents -'ORM PO-1OSO (10-69) USCOMM-DC 60376-P69 a u4sv GOVERNMENTPRINTING OFFICE: l9" O--368-334

1. In a combination with a tuyere passing through the steel mantle andthe refractory masonry of a convertor, for reliably feeding oxidizingrefining gases surrounded by a liquid or gaseous protective medium intoa molten metal bath, said tuyere being disposed to discharge said fluidsunderneath the metal bath level, the refining gas being supplied to saidmolten metal through an inner tuyere pipe and the protective mediumbeing supplied through an annular space between the inner tuyere pipeand an outer, coaxial pipe, said outer pipe leading to a supply cap orhead surrounding a sleeve of the inner through-pipe and a closure forthe outer tuyere pipe; the improvements which comprise: providingseparate connections between said supply cap (13) and said inner tuyerepipe (2) and spatially separate supply sources (21, 29) respectively,for the protective medium and the refining gas, means hermeticallysealing said sleeve (10) peripherally with the inner tuyere pipe (2) bywelding or soldering, metallic sealing rings located axially on bothsides of said supply cap for sealing said supply cap wIth respect to theouter typere pipe (1) and with respect to the sleeve (10), and means foraxially tensioning said metallic sealing rings on both sides.
 2. Atuyere as defined in claim 1 including in addition clamping nuts orscrew caps (1, 15) mounted on the supply cap (13) for tensioning thesealing rings (9,16), said sealing rings being detachable.
 3. A tuyereas defined in claim 1 wherein the extremities of sleeve (10) and of theouter tuyere pipe (1) are axially separated from each other and alongitudinally adjustable annular space (12) is formed between them. 4.A tuyere as defined in claim 1 including, in addition a putty seal ormastic seal between the outer surface of the outer tuyere pipe (1) andsteel mantle (5). 11
 5. In the tuyere as defined in claim 1, themetallic sealing rings (9, 16) and the putty or mastic (8) are eachtemperature resistant up to 300* C.
 6. A tuyere as defined in claim 4wherein the putty or mastic consists principally of SiO2-Al2O3, which isprepared from water glass and/or phosphoric acid solutions or withadditions of cement and water.
 7. A tuyere as defined in claim 1including in addition ball joint connections (28) mounted in the supplylines (17, 27, 14) to the outer tuyere pipe (1) and to the supply cap(13).